TPO Roof Cost Calculator

The estimate starts at $6.50 to $11 a square foot

TPO costs about $6.50 to $11 a square foot installed, or $650 to $1,100 a square, according to our TPO roofing guide. That price includes the membrane, about 2 inches of polyiso insulation, fasteners and plates, edge metal, flashings and labor. Tear-off is extra.

The tool doesn't use that whole range for every roof. It picks a band $2.25 wide inside it, set by the thickness and attachment you choose, then adds separate lines for the extras.

• Base rate: $6.50 to $8.75 a sq ft for 45 mil mechanically fastened, up to $8.75 to $11 for 80 mil fully adhered or induction welded
• Material and labor split: about $300 to $500 material and $350 to $600 labor per square, the same split the roof cost calculator uses
• Tear-off: $1 to $1.50 a sq ft for each layer removed
• Code-level polyiso (4 inches or more): $2 to $4 a sq ft
• Tapered insulation: another $2 to $4 a sq ft
• Busy roof: 20 to 30 percent more on the membrane and labor lines
• ZIP code: labor times your state's roofer wage over the national average

Worked example: a 40 x 30 garage roof

The default inputs are a 1,200 sq ft garage roof, 40 by 30 feet, with 60 mil TPO mechanically fastened and one old layer torn off. That combination sits at $7.25 to $9.50 a square foot, so the membrane system comes to $8,700 to $11,400.

Tear-off adds $1,200 to $1,800. The total is $10,630 to $14,630, or $8.85 to $12.19 a square foot and $890 to $1,220 a square.

On 10-foot rolls, the membrane takeoff is about 1,437 sq ft with waste, which means 2 rolls and 120 feet of welded seam. Switch to 80 mil fully adhered and add code-level and tapered insulation, and the same roof runs $17,380 to $26,250.

Thickness and attachment set where you land in the range

TPO comes in 45, 60 and 80 mil. Most of the extra thickness goes into the top ply that weathers away, and 60 mil is what most contractors recommend for houses. It costs a little more in material than 45 mil and about the same in labor, so the tool moves you one step up the range for each jump in thickness.

Attachment works the same way. Mechanically fastened is the cheapest, with screws and plates hidden in the seams. Fully adhered sheets are glued to the insulation or a cover board, which takes more adhesive and labor. Induction welding bonds the sheet to plates from above and resists wind nearly as well as glue, though not every residential roofer owns the equipment.

What adds to the price of a TPO roof?

Tear-off, insulation and penetrations add the most. Taking off an old roof costs $1 to $1.50 a square foot per layer, more for heavy gravel or soaked insulation. Choosing zero layers means a recover, which saves that cost but only works on a dry, solid roof with one existing layer.

Insulation can move the budget a lot. Energy codes often call for several inches of polyiso, and going past the standard 2 inches adds $2 to $4 a square foot. Tapered board, cut to slope the roof toward drains, adds about the same again. The flat roof guide is the source for these add-ons.

Penetrations matter almost as much as size. Every pipe, drain and curb gets hand-welded flashing, and every wall needs termination bar and sealant. A roof crowded with skylights and HVAC units runs 20 to 30 percent more, almost all of it labor. The calculator scales that extra with the drains, pipes and curbs you enter, reaching the full amount at about one per 100 sq ft. Tick the busy box if the roof also has units the counts don't cover. Many good installers also add a gypsum or high-density cover board over the foam. Our guides don't give it a separate price, so get it quoted if you want one.

What the estimate leaves out

Rotten decking from slow leaks is the most common surprise, at $80 to $120 a sheet of plywood. A three-story job that needs a crane adds $500 to $1,500 to the mobilization fee. Taller walls may need their flashing raised once thick insulation lifts the roof surface.

Material prices are national. The ZIP code only adjusts labor, using the BLS roofer wage data for your state. Treat the result as a check on bids, not a bid.

Compare bids line by line

A good written TPO estimate names the manufacturer and product line, the membrane thickness, the insulation type and total R-value, the attachment method, the edge metal, and how the membrane ends at walls. A price per square with none of that detail is a red flag, because termination bars, edge metal and sealant keep a roof dry as much as the membrane does.

Put each bid next to the breakdown above. If one quote is far below the range, check whether it drops the tear-off, skips new insulation or uses 45 mil sheet. If it's far above, ask whether it includes code-level insulation, tapered board or deck repair. Then ask the crew whether they test-weld every morning and probe every seam at the end.

When another flat roof system makes more sense

TPO suits most sunny houses with a flat roof that nobody walks on. Its white surface keeps the house cooler, and its seams are welded into one sheet. Other membranes fit some roofs better.

• Modified bitumen for decks and foot traffic. At $5.50 to $9 a square foot, it costs less and takes more abuse. The TPO vs modified bitumen comparison covers the trade-offs.
• PVC near grease or chemicals. Kitchen exhaust softens TPO, and PVC resists it, at a higher price.
• EPDM for the longest record in cold climates. The black rubber membrane is often cheaper, though its seams are taped. See the EPDM guide.

To compare all three single-ply membranes with a full takeoff, use the flat roof calculator.